The invention relates to a differential amplifier having a differential input signal, and a single-ended output signal with two pairs of differential amplifiers. Modern CMOS technologies such as those used by ChipIdea Microelectronica, Lisbon, Portugal, (as well as by other companies) allow dimensions of microelectronic circuits and levels of supply voltages on supply rails to be scaled down with respect to older technologies. However, interfaces to circuits with which CMOS circuits must operate are standardized to operate at particular voltage levels not necessarily compatible with CMOS. Many of these interface standards have not been updated despite a trend in the industry to decrease the supply voltages on supply rails. Digital SOCs take advantage of a reduction in supply voltage to allow the reduction of silicon area and to increase the speed of operation of microelectronic circuits.
One requirement in designing analog circuits which are included in SOCs is that the analog circuits need to be compliant with existing standards. For example, the specification of USB 2.0 requires a supply voltage of 3.3V in LS/FS mode on a supply rail. However, the circuit might be implemented using CMOS devices which operate at the supply voltage of 1.8V or 2.5V. As a result, it is possible that the input signal at 3.3 V must be processable using the CMOS devices operating at the supply voltage of 1.8V or 2.5V.
There is also a requirement in circuit design techniques to provide an amplifier in a receiver which ensures proper operation of the receiver without any degradation or life-time reduction of the receiver and, in particular, of the CMOS devices within the receiver.